Aoiro Toshokan

Seishoku Toshokan, The Blue Library

Desperate to get her hands on a gown she saw on her way home from school, Hina jumps into "Aoiro Toshokan" for a part-time work. There, she ends up working under the Library Director who is also an author known as Shimokomoriya. Thus begins Hinas's boring days with the handful Sensei.